Screw pump



Fatenteel Der. 29,. i925,

SCREW PUMP.

' Application led July 28, 1925. Serial No. 45,581.

To all 'whom it may concern.'

Be it known that l. EMANUEL llloclolm- BA, a" citizen of thevRepublie of Germany, residing at litheinbiwh` Germany, havel invented new and useful lmprovenwuts in Screw Pumps (for which l have. tiled an application in Germany, M. 81.862, June 16, 1924), of which the following is a specification.

My invention relates to pumpsl and specifically to the type known as screw pumps.

Positive acting pumps comprising oppositely rotating intermeshing worm shafts are Well known. Une of the disadvantages of `this type of pump lies in the fact that absolute contact etween the teeth of one shaft and the grooves of the other is possible only in one plane, viz, a lane assing through the axes of both sha s. Tiis is due to the nature of the warped surfaces constituting the sides of the teeth. Asda. result, a certain lamount of leakage occursfthrough the contaeting sides of the shafts from the high pressure end of the ump. to the low `pressure end thereof. This impairs th'e eftciencv of the pump and prevents its use at high speeds or for high pressures.

The object of my invention is to lobviate this disadvantage and I achieve this result by eliminating the true helical tooth of the ordinary type and substituting therefor a substantially helical and continuous toothy comprising alternate stepped portions parallel and perpendicular to the axis of the shaft. Accordingly, none of the sides of the teeth are warped surfaces but are lanes, and absolute kcontact over a consi erable area is thereby assured. l i

For the purpose of more fully describing my. invention, reference will be had to the accompanying drawings, in which- Fig. l is a plan view of a pump embodying my invention, partly in section;

Fig. 2 is a cross section taken along the lino 2-2 of Fig. 1;

Figs. 3 and 4 are enlarged plan views of corresponding portions of the two improved worm shafts.

Referring to the drawings, 10 denotes a casing or housing of the usual type having bearings 11 in opposite ends thereof adapted to receive the opposite ends of the worm shafts. One of said bearings extends entirely through the end of the housing so that the shaft may extend therethrough and be 55 connected with the driving means, as will be understood. At opposite ends of the housing are also the inlet and outlet openings12 and 13.

Two iutermeshing parallel worm shafts 14 00 and 15 are journallcd in the bearings 11, and the housing is of such construction and shape as to closely embrace the outer peripheries of the shafts. as shown in Fig. 2. The shafts are providedwith adjacent intermesh- 05 ing spur gears 1G near one end of the housing whereby an opposite rotation is imparted to them by the driving of one of them.

Referring now to Figs. 3 and 4. each shaft is provided with a continuous helically disposed tooth 17 having alternate stepped portions 18, lying in planes perpendicular to the axes, and 19. lying in planes parallel to and passing through the axes. The side surfaces of these teeth are therefore plane 7 surfaces, and positive intermeshing is thercby assured. It will be apparent from a eonsideration of Figs. 3 and 4 that the space between the raised portions of the tooth constitutes a continuous channel 20 through 80 which the liquid being pumped isforeed in a steady stream from one end to the other by the intermeshing tooth of the other shaft Thus if the arrows 21 of Figs. 1 and 2 d enote the direction of turning, the liquid will be drawn into the inlet opening 12 and be forced through the channels 20 in a manner as indicated by arrows 22, to the outlet or discharge opening 13. Duringl this passage, the absolute contact between the shafts along their intermeshing edges will prevent any leakage back from the pressure to the suction side.

I do'not. wish to limit myself to the actual structure illustrated. since it is conceivable "5 that without departing from the spirit. of the invention the .worm shafts may be doul ble or mu1ti-threaded, or that the widtl'. .o f

the tooth and groove may varyat different portions; for example the Width may' be 100 `slightly decreased toward the discharge side I 2. A screw pump comprising oppositely to accord with the increased pressure.

What I claim is 1. In a screw pump ofthel character de- 5 scribed, a worm shaft in which the continuous helical tooth hasalternate stepped portions parallel and perpendicular to the axis.

rotatin vintermeshing Worm shafts, each of which as a continuous helical tooth having alternate stepped portions parallel and perpendicular to the axis.

vIn testimony whereof I aiix my signature.

EMANUEL MOCIGEMBA. 

